Note: Descriptions are shown in the official language in which they were submitted.
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STEERING ASSEMBLY FOR DIRECTIONAL DRILLING OF A WELLBORE
Cross-Reference to Related Applications
This application is a PCT filing of and claims priority to Patent Application
Number US
16/378421 filed April 8, 2019, the entire disclosure of which is herein
incorporated by reference.
Field of the Invention
The present invention relates to the field of directional drilling systems and
to a method
for controlling the direction while drilling a vertical or horizontal
wellbore. More particularly, the
present invention is related to a steering assembly to be included in a drill
string for directional
drilling.
Background
Directional drilling systems are systems well known in the art of drilling oil
and gas
wellbores. Such a system generally comprises a drillstring with a bottom hole
assembly (BHA)
comprising a steering assembly and a drill bit attached to the bottom end of
the drillstring.
In directional drilling, the bottom hole assembly generally comprises a
measurement
while drilling assembly (MWD) comprising sensors for measuring information
about the
direction (inclination and azimuth) of the wellbore and other downhole
drilling parameters, and
comprises telemetry transmitters for transmitting sensor data uphole to a
surface control unit.
Additionally, for directional control, a conventional bottom hole assembly
comprises a downhole
motor and bent sub coupled to a shaft for rotating the drill bit. Optionally,
a rotary steerable
system (RSS) may either replace or be used in combination with the downhole
motor to provide
steering control. The advantage of the RSS is to allow directional steering
control while rotating
the entire drillstring, whereas the downhole motor alone is only steerable by
holding the
drillstring fixed in a particular direction (or toolface) from the surface.
The benefits of
continuously rotating the drillstring are numerous including a large reduction
in friction between
the drillstring and the borehole, which permits the drilling of longer
distance horizontal wells.
Rotary Steerable Systems generally comprise a tubular housing enclosing a
shaft having a
front end connected directly or indirectly to the drill bit. Various kinds of
steering mechanisms
can be included in the housing to change the orientation of the front end of
the shaft to change
the direction of drilling. A first category of rotary steerable systems is
configured to work in a
"push the bit" mode, and a second category of rotary steerable systems is
configured to work in a
"point the bit" mode. In push the bit mode, the bit dominant factor of
steering is a side (or lateral)
force imparted to the bit. In point the bit mode, the dominant factor for
steering is an angular
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change or tilting of the bit. Each category of rotary steerable systems is
comprised of further
sub-categories.
For the rotary steerable systems configured to work in push the bit mode, the
housing
comprises pads or some other offset mechanism which can be selectively
activated for applying a
reactive side force on the shaft, thus changing the orientation of the drill
bit.
A first sub-category of push the bit rotary steerable systems comprises a non-
rotating (or
slowly rotating) housing provided by a plurality of pads distributed around
the circumference of
the housing and directed towards the wellbore. The pads are selectively
actuated to push against
the wellbore formation and change the orientation of the housing which
deflects the shaft and
provides the required side force on the drill bit, thus deflecting the drill
bit sideways in a
preferred direction of drilling.
A second sub-category of push the bit rotary steerable system comprises a non-
rotating
(or slowly rotating) housing provided by a fixed body-mounted stabilizer and a
deflection device
inside the circumference of the housing and directed towards the shaft. The
internal deflection
device is selectively actuated to push the shaft away from the center of the
stabilized housing and
thus the center of the wellbore, providing a side force on the drill bit.
Another sub-category of push the bit rotary steerable system comprises a
rotating housing
provided by a plurality of pads distributed around the circumference of the
housing and directed
towards the wellbore. The pads rotate with the housing and can independently
move from a
retracted to an extended position, bearing against the wellbore formation and
pushing the housing
laterally off-center from the wellbore, thus changing its orientation. The
system further comprises
a control means that actuates one pad when the pad crosses a selected radial
angle such that the
pad pushes against the wellbore towards a selected direction to change the
orientation of the
housing which deflects the shaft and provides the required offset force at the
drill bit. While
drilling in soft formations, it may not be suitable to use a steering system
which pushes pads
against the wellbore, especially when rotating said pads.
For the rotary steerable systems configured to operate in point the bit mode,
the primary
method used to tilt the drill bit is to bend the shaft inside a centralized
non-rotating (or slowly
rotating) housing, thus angularly deflecting the shaft away from the
centerline axis of the
wellbore. In that case, the non-rotating housing includes some form of anti-
rotation means and a
mechanism for deflecting the shaft inside the non-rotating housing. In this
case, bending while
rotating the shaft can cause fatigue on the shaft, and the shaft may break or
get deformed after a
certain time of use. Workarounds include the use of costly materials and may
require an
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increased shaft diameter this limiting the available cross-section for offset
mechanisms, power,
and instrumentation.
Beside the category of "push the bit" and "point the bit" rotary steerable
systems, there
also exist hybrid rotary steerable systems that are capable of steering like
both a push the bit and
point the bit system, depending on configuration. An example of such a hybrid
rotary steerable
system is disclosed in US patent No 7,188,685. This rotary steerable system
comprises an upper
section connected to a steering section and a drill bit connected to the
steering section. The upper
section is connected to a collar on which an upper stabilizer is provided. The
steering section
comprises a lower stabilizer and is connected to the upper section by a swivel
which is a two
degree of freedom universal joint, such that the swivel is located between the
lower stabilizer and
the drill bit. Pistons are located between the steering section and the upper
section and are
actuated to push against the steering section which pivots on the universal
joint. The steering
section tilts until the lower stabilizer contacts the formation at which point
the pistons act to push
the bit through the formation. As the formation is drilled, the constraint
imposed by the formation
is removed, the periphery of the steering section is allowed to tilt further
and the tool then begins
to steer as a point the bit system. Rotation of the steering section against
the pads causes friction
that can produce wear of those parts and vibration of the steering section
which can influence the
quality of the borehole.
It is desirable to provide a rotary steerable system that doesn't present the
drawbacks of
prior art devices, and which provides:
- wellbore steering in either push the bit or point the bit mode;
- a point the bit mode which minimizes internal cyclic bending stresses;
- relatively high turn rates (or dogleg severity);
- a configuration that is easily field serviceable;
- the capability to vary turn rate (or dogleg severity) while providing
independent
directional tool face control and;
- good control of the direction of drilling with less vibration.
Summary of the Invention
According to a first aspect, the present invention is related to a Steering
assembly 100
comprising a housing 136 having a longitudinal axis 101 and a mandrel 102
comprising a front
connecting extremity 103 and a rear connecting extremity 104, the mandrel 102
passing through
the said housing 136 and arranged in a first position coaxially to the said
longitudinal axis 101 of
the housing 136, the steering assembly being characterized in that it
comprises:
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- a deflector device for giving a side force to the said mandrel 102 such
as to bring the
said front connecting extremity 103 of the said mandrel 102 offset from the
said
longitudinal axis 101, and
- a tool face assembly for rotating the said front connecting extremity 103
of the said
mandrel 102 towards a desired direction;
the said mandrel 102 being rotatable relative to the said housing, the said
deflecting
assembly and the said tool face assembly.
Preferably, the mandrel 102 is connected to the housing 136 through a bearing
pack
comprising a spherical seat 105 arranged around a set of ball bearings 130.
Preferably, the said toolface assembly comprises:
- an orienting sleeve 106 at least partially included in the said housing
136 and arranged
around the said mandrel 102, the said orienting sleeve 106 comprising a first
sleeve
section 106a having a bore coaxial with the said longitudinal axis 101 of the
housing
136 and a second sleeve section 106b having a bore coaxial to a second axis
137
inclined relative to the said longitudinal axis 101 of the housing 136; and
- an actuating system for rotating the said orienting sleeve 106;
Preferably, the said deflector device is a deflecting assembly comprising:
- a deflecting sleeve 107 arranged around the said mandrel 102 and
coaxially to the said
second axis 137 and;
- an actuating system for moving the said deflecting sleeve 107 along the said
second
axis 137.
Preferably, the said actuating system for rotating the said orienting sleeve
106 comprises a
first geared actuator 108 that engages a geared surface 109 of the said
orienting sleeve 106.
Preferably, the said actuating system for moving the said deflecting sleeve
106 along the said
second axis 137 comprises:
- a first actuating sleeve 110 surrounding the said mandrel 102 and at
least partially
included into the said first sleeve section 106a of the orienting sleeve 106,
the said
first actuating sleeve 110 comprising:
o a geared surface 111, and
o a geared extremity 112 directed towards the bore of the second sleeve
section
106b of the said orienting sleeve 106;
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- a second geared actuator 113 that engages the said geared surface 111 of
the first
actuating sleeve 110;
- a second actuating sleeve 114 surrounding the said mandrel 102, included
into the
said second sleeve section 106b of the orienting sleeve 106, retained by an
abutment
115 into the said second sleeve section 106b and disposed around the said
deflecting
sleeve 107, the second actuating sleeve 114 comprising:
o a geared extremity 116 that engages the said geared extremity 112 of the
said
first actuating sleeve 110 and;
o a spiral guiding means 117 provided on its the inner surface;
o a linear guiding means 118 provided into the said second sleeve 106b section
of the orienting sleeve 106;
Preferably, the said deflecting sleeve 107 comprises:
- a first side comprising a spiral cam follower 119 that engages into the
said spiral
guiding means 117 in the second actuating sleeve 114;
- a second side comprising a second cam follower 120 that engages with the
said linear
guiding means 118.
Preferably, an assembly of a spherical seat 121a and ball bearing 121b is
arranged between the
said deflecting sleeve 107 and the said mandrel 102.
Preferably, the external surface of the said housing 136 further comprises
bore contact pads
122.
Preferably, the said housing 136 further comprises one or more enclosures 123
including a
battery 124, a control electronic assembly 125 and a motor 126, 127.
Preferably, the steering assembly comprising a first motor 126 and a first
geared actuator 108
dedicated for rotating the said orienting sleeve 106, and a second motor 127
and a second geared
actuator 113 dedicated for rotating the first actuating sleeve 110 of the
actuating system for
actuating the deflecting sleeve 107.
In a first possible configuration, the steering assembly further comprises a
pivot stabilizer sub
131 connected to the said rear extremity 104 of the mandrel 102.
In a second possible configuration, the steering assembly further comprises a
pivot sub 135
connected to the said front extremity 103 of the mandrel 102 and connected to
a near bit
stabilizer sub 133 having its blades 134 away from the pivot point 139 of the
pivot sub 135, and
itself connected to a drill bit 200.
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Preferably, the said housing is configured for not rotating in the wellbore
and serves as a
reference point for steering the bit.
More preferably, the steering assembly further comprises a control electronic
assembly 125
configured for measuring any undesirable rotation of the housing in the
wellbore, calculating the
correction to apply to steer the bit in the desired direction and to apply
these corrections to the
said deflecting assembly and tool face assembly.
In a second aspect, the present invention relates to a method for
directionally drilling a
wellbore by providing the steering assembly 100 in a drillstring as presented
in the present
disclosure, and wherein the magnitude of the directional steering is changed
by operating the said
deflector device.
In the method of the present invention, the steering direction can be further
changed by
operating the said tool face assembly.
In a first embodiment of the method of the present invention, the said
steering assembly 100
is used in a push the bit configuration with the said front extremity 103 of
the mandrel 102
connected to a drill bit 200.
In a second embodiment of the method according to the present invention, the
said steering
assembly 100 is used in a point the bit configuration wherein the said front
extremity 103 of the
mandrel 102 is connected to a second pivot sub 135 itself connected to a near-
bit stabilizer sub
133, itself connected to a drill bit 200.
The present invention can also be described as a steering assembly 100
comprising a housing
136 having a longitudinal axis 101 and a mandrel 102 comprising a front
connecting extremity
103 and a rear connecting extremity 104, the mandrel 102 passing through the
said housing 136
and arranged in a first position coaxially to the said longitudinal axis 101,
a deflector device for
giving a side force to the said mandrel 102 in the housing 136 such as to
bring the said front
connecting extremity 103 of the said mandrel 102 offset from the said
longitudinal axis 101,
characterized in that it further comprises a pivot stabilizer sub connected to
the rear extremity of
the mandrel.
Preferably, the said pivot stabilizer sub is arranged outside of the housing.
In another embodiment of the invention, the front extremity 103 of the mandrel
102 is
connected to a pivot sub 135, itself connected to a near bit stabilizer 133
which is directly
connected to a drill bit 200. Further, the near bit stabilizer and the bit may
be combined into one
unit.
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Preferably, the said housing is configured for not rotating or slowly rotating
within the
wellbore and serves as a reference point for steering the bit.
Preferably, the steering assembly comprises:
- a deflector device for producing a side force to the said mandrel 102
into the housing
136 such as to bring the said front connecting extremity 103 of the said
mandrel 102
offset from the said longitudinal axis 101, and
- a tool face assembly for rotating the said front connecting extremity 103
of the said
mandrel 102 towards a desired direction;
the said mandrel 102 being rotatable relative to the said housing, the said
deflector device and the
said tool face assembly.
Preferably, the steering assembly comprises a control device configured for
measuring any
undesirable rotation of the housing in the wellbore, calculating a correction
to apply to steer the
bit in the desired direction and to apply these corrections to the said
deflector device and tool
face assembly.
In a method for drilling directionally a wellbore according to the present
invention, a steering
assembly 100 such as presented in the present disclosure is provided in a
drill string, and the
magnitude of the direction of drilling is changed by providing a side force on
the said mandrel.
In the said method, the tool face assembly can be operated for changing the
tool face of the drill
bit.
Brief description of the drawings
Figure la shows a cross sectional view of a steering assembly according to an
embodiment of the present invention, the steering assembly being connected to
a drill bit.
Figure lb shows a cross sectional view of a steering assembly according to an
embodiment of the present invention, the steering assembly being connected to
a pivot stabilizer
sub itself connected to a drill bit.
Figure 2a shows an enlarged cross sectional view of a first section of the
steering
assembly according to the embodiments presented in figures la and lb.
Figure 2b shows an enlarged cross sectional view of a second section of the
steering
assembly according to the embodiments presented in figures la and lb.
Figure 3 shows an enlarged cross sectional view of a front section of the
steering
assembly according to the present invention.
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Figure 4 shows a three dimensional exploded view of the front section of the
steering
assembly presented in figure 3.
Figure 5 shows a three dimensional view of the inside of the first section of
the steering
assembly presented in figure 2a.
Figure 6 illustrates a cross-sectional view of a portion of a steering
assembly in
accordance with implementations of various techniques described herein.
Figure 7 illustrates a cross-sectional enlarged view of the steering assembly
in accordance
with implementations of various techniques described herein.
Figure 8 illustrates a cross-sectional enlarged view of the steering assembly
in accordance
with implementations of various techniques described herein.
Figure 9 illustrates a cross-sectional view of a portion of a steering
assembly in
accordance with implementations of various techniques described herein.
Figure 10 illustrates a cross-sectional view of the steering assembly in
accordance with
implementations of various techniques described herein.
Figure 11 illustrates a front cross-sectional view of the steering assembly in
accordance
with implementations of various techniques described herein.
Figure 12 illustrates a cross-sectional view of the steering assembly in
accordance with
implementations of various techniques described herein.
Figure 13 illustrates a block diagram of a hardware configuration in which one
or more
various technologies described herein may be incorporated and practiced.
Detailed Description
According to a first aspect, the present invention relates to a steering
assembly 100 to be
included in a drill string for steering a drill bit in a directional wellbore.
A steering assembly according to the present invention comprises a housing 136
having a
longitudinal axis 101 and a mandrel 102 comprising a front connecting
extremity 103 for
connection to a drill bit 200 and a rear connecting extremity 104 for
connection to a drill string,
the mandrel 102 passing through the said housing 136 and being arranged in a
first position
coaxially to the said longitudinal axis 101. The steering assembly being
characterized in that it
comprises:
- a deflector device for pivoting the said mandrel 102 in the housing 136 or
in other
words to give a side force on the mandrel such as to bring the said front
connecting
extremity 103 of the said mandrel 102 offset from the said longitudinal axis
101, and
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-
a tool face assembly for rotating the said front connecting extremity 103
of the said
mandrel 102 towards a desired direction;
the said mandrel 102 being rotatable relative to the said housing, the said
deflecting assembly and
the said tool face assembly.
Preferably, the deflector device is a deflecting assembly as presented herein
above.
Alternatively, the deflector device can be any deflector device known by the
man skilled in the
art such as for example pistons or pads arranged in the housing 136 to push
the mandrel 102 and
actuated by an actuator.
The figure la presents a cross sectional view of an embodiment of a steering
assembly
configured in a "push the bit" mode. The term "push the bit" is used as
reference to the
configurations "push the bit" of the prior art steering systems wherein a side
force is applied on
the mandrel to change the offset of the mandrel relative to the axis of the
housing. In the present
invention, bending of the mandrel is minimized by connecting the rear
extremity 104 of the
mandrel 102 to a pivot stabilizer sub 131 such that when a side force is
applied on the mandrel
102, the mandrel rotates relative to the pivot point and the front extremity
103 of the mandrel 102
gets offset from the axis of the housing. The front extremity of the mandrel
is connected to a drill
bit 200.
Advantageously, the pivot stabilizer sub 131 is arranged outside of the
housing 136. This
arrangement simplifies the construction and the manufacturing of the steering
assembly, and the
pivot stabilizer sub 131 can be removed and replaced easily. The pivot
stabilizer sub 131 also
gives more flexibility to the steering assembly and a wellbore can be drilled
with higher doglegs.
The figure lb presents a cross sectional view of a the same steering assembly
represented
in figure la with additional means arranged between the front end 103 of the
mandrel 102 and
the drill bit 200 such that the steering assembly is configured in a "point
the bit" mode. The rear
extremity 104 of the mandrel 102 is connected to a first pivot stabilizer sub
131 and the front
extremity 103 of the mandrel 102 is connected to a pivot sub 135, which is
connected to a near
bit stabilizer 133, which is connected to a drill bit 200. The near bit
stabilizer 133 has blades 134
located away from the pivot point 139 of the pivot sub 135, in order to obtain
a better "point the
bit effect" wherein the blades acts as a pad stabilizer preventing the side of
the bit to cut the
formation and maintaining borehole centralization at that point. In that
configuration, when a
force is applied on a lateral side of the mandrel 102, the mandrel rotates
about the pivot point
131' of the pivot stabilizer sub 131, the front extremity 103 of the mandrel
points towards a first
direction at an angle a relative to the longitudinal axis 101 of the housing
136. The pivot sub 135
allows the drillstring to dislocate from the center or the wellbore. A fulcrum
formed by the near
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bit stabilizer 133 and the wall of the wellbore causes the drill bit to point
towards a second
direction at an angle f3 relative to the longitudinal axis 101 of the housing,
wherein the angle f3 is
directly proportional to a but in the opposite direction, depending on the
distance between the
fulcrum point and the bit.
These both aforementioned configurations present the advantage that the
mandrel 102 is
not bent while applying changes to the orientation of the drill bit so that
the fatigue on the
mandrel is reduced, and therefore the durability of the steering assembly and
the directional
control of the drill bit are improved. Advantageously, the pivot sub 135 is
also outside the
housing 136 to simplify the construction of the steering assembly and to
facilitate maintenance.
The figure 2a shows an enlarged view of a first section of the steering
assembly according
to an embodiment of the present invention. The mandrel 102 is connected to the
housing 136
through a bearing pack comprising a spherical seat 105 connected to the inner
surface of the
housing 136 and arranged around a set of ball bearings 130 that allows free
rotation of the
mandrel 102 relative to the housing 136. The spherical seat 105 is arranged
between the mandrel
102 and the housing 136 such as to allow pivotal movement of the mandrel 102
relative to the
housing 136 and provides radial and/or axial load coupling between the mandrel
102 and the
housing 136. Preferably, the bearing pack is arranged in the vicinity of the
rear end of the
housing and the rear extremity 104 of the mandrel 102.
A more detailed three dimensional view of the inside of the housing 136 is
presented in
figure 5. The housing 136 comprises compartments or enclosures 123 for
arranging one or more
batteries 124, control electronics assemblies 125 and motors 126 and 127 for
communicating
with the surface and operating the deflecting assembly and the tool face
assembly.
The figure 2b represents an enlarged view of a second section of the steering
assembly
showing the tool face assembly and the deflecting assembly. The said tool face
assembly
comprises an orienting sleeve 106 included in the said housing 136 and
arranged around the said
mandrel 102. The orienting sleeve 106 comprises a first sleeve section 106a
having a bore
coaxial with the longitudinal axis 101 of the housing and a second sleeve
section 106b having a
bore coaxial to a second axis 137 which is inclined relative to the said
longitudinal axis 101 of
the housing. Preferably, the outer surface of the second sleeve section 106b
is cylindrically
coaxial to the longitudinal axis 101 of the housing 136 and has an outer
diameter adapted to
prevent debris of the wellbore to penetrate within the housing. For example,
the outer diameter of
the second sleeve section 106b is superior or equal to the outer diameter of
the end of the housing
136 carrying the orienting sleeve 106. Alternatively, the outer diameter of
the second sleeve
section 106b may be substantially equal or superior to the inner diameter of
the end of the
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housing 136 carrying the orienting sleeve 106. Because of the inclination of
the bore of the
second sleeve section 106b along the second axis 137, the outer diameter of
the second sleeve
section 106b is superior to the diameter of the first sleeve section 106a of
the orienting sleeve.
To provide a more compact steering assembly, it is preferable that the
orienting sleeve 106 be
partially included in the housing 136, with the first sleeve section 106a
arranged inside of the
housing 136 and the second sleeve section 106b arranged outside of the housing
136. Preferably,
at least one bearing, preferably a thrust bearing 132 is arranged between the
housing 136 and the
orienting sleeve 106. The toolface assembly further comprises an actuating
system for rotating
the orienting sleeve 106, the actuating system comprising preferably a first
geared actuator 108
that engages a geared surface 109 of the orienting sleeve. The first geared
actuator 108 is
arranged in the housing 136 and can be powered by a motor 126. The geared
surface 109 is
preferably arranged at the outer surface of the first sleeve section 106a
inside the housing.
The deflecting assembly comprises a deflecting sleeve 107 arranged around the
said mandrel
102 and coaxially to the said second axis 137. Preferably, the deflecting
sleeve is arranged inside
the second sleeve section 106b of the orienting sleeve 106. The deflecting
assembly further
comprises an actuating system for moving the said orienting sleeve 107 along
the said second
axis 137.
An embodiment of an actuating system for moving the deflecting sleeve 107 is
presented
herein above in combination with the figures 2b, 3 and 4. The actuating system
for moving the
deflecting sleeve 107 comprises a first actuating sleeve 110 that surrounds
the mandrel 102 and
that is at least partially included in the first sleeve section 106a of the
orienting sleeve 106, so
that the geared surface 111 can be engaged by a second geared actuator 113
arranged into the
housing 136. The second geared actuator 113 can be powered by a second motor
127. The first
actuating sleeve 110 further comprises a geared extremity 112 directed towards
the bore of the
second section 106b of the said orienting sleeve 106. A second actuating
sleeve 114 is included
inside the said second sleeve section 106b of the orienting sleeve 106,
coaxially to the said
second axis 137, and is retained by an abutment 115 into the said second
sleeve section 106b.
The second actuating sleeve 114 surrounds the said deflecting sleeve 107 which
is disposed
around the said mandrel 102. The second actuating sleeve 114 comprises:
- a geared extremity 116 that engages the said geared extremity 112 of the
said first
actuating sleeve 110 and;
- a spiral guiding means 117 provided on its the inner surface.
The said deflecting sleeve 107 comprises:
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- a first side comprising a spiral cam follower 119 that engages into the
said guiding
means 117 in the second actuating sleeve 114;
- a second side comprising a linear cam 120 that engages with a linear
guiding means
118 provided in the said second sleeve 106b section of the orienting sleeve
106.
The deflecting sleeve 107 is connected to the mandrel 102 through a bearing
pack comprising a
spherical seat 121a and ball bearing 121b. The spherical seat 121a is arranged
between the said
deflecting sleeve 107 and the ball bearing 121b itself arranged around the
said mandrel 102. A
clearance between the inner surface of the deflecting sleeve 107 and the outer
surface of the ball
bearing 121b allows a rotational movement of the ball bearing 121b relative to
the deflecting
sleeve 107, centered on the axis 138 of the spherical seat 121a.
To deflect the mandrel axis 101' relative to the axis 101 of the housing,
instructions are
sent to the control electronic assembly 125 for actuating the second geared
actuator 113 to rotate
the first actuating sleeve 110 whose geared extremity 112 engages the mating
geared extremity
116 of the second actuating sleeve 114 inclined relative to the first
actuating sleeve 110. Said
instructions are sent to the control electronic assembly for example via
telemetry transmitters.
The inner surface of the second actuating sleeve 114 comprises a spiral
guiding means 117
engaging the spiral cam follower 119 of the deflecting sleeve 107. The spiral
cam follower 119 is
preferably arranged on the rear side of the deflecting sleeve 107 oriented
towards the first
actuating sleeve 110. The front side of the deflecting sleeve 107 which is
oriented towards the
front end 103 of the mandrel 102 comprises a second cam follower 120 that
engages within the
linear guiding means 118 which is fixed in the second sleeve section 106b of
the orienting sleeve.
The linear guiding means 118 is prevented to rotate together with the second
actuating sleeve so
that the rotation of the second actuating sleeve 114 causes the deflecting
sleeve 107 to translate
along the said second axis 137 of the bore of the second sleeve section 106b
of the orienting
sleeve 106. This action deflects the mandrel 102 from a position parallel to
the axis 101 of the
housing 136 to a second position inclined relative to the axis 101 of the
housing 136. The bearing
pack arranged between the deflecting sleeve 107 and the mandrel 102 allows
free rotation of the
mandrel 102 relative to the deflecting sleeve 107 and to the orienting sleeve
106 and provides
structural coupling between the parts.
Alternative embodiments of a deflecting assembly including various embodiment
of a
deflecting sleeve 107 and means for pushing the deflecting sleeve 107 along
the said second axis
137 can be envisaged by the man skilled in the art such as for example a
deflecting sleeve
actuated by piston means or scissors powered by a motor.
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To orient the mandrel 102 towards a desired direction or in other words to
change the tool
face of the drill bit, instructions are sent to the control electronic
assembly 125, for example via
telemetry transmitters, for actuating the first geared actuator 108 for
rotating the orienting sleeve
106. The control electronics may also operate and provide directional control
independent of
surface commands via preprogrammed computer algorithms.
In a preferred embodiment of the present invention, the housing 136 of the
steering
assembly comprises an enclosure for a first motor 126 connected to the first
geared actuator 108
dedicated for rotating the said orienting sleeve 106, and for a second motor
127 connected to the
second geared actuator 113 dedicated for rotating the first actuating sleeve
110 of the actuating
system for actuating the deflecting sleeve 107. In such an embodiment, it is
therefore possible to
send instructions for deflecting the mandrel at a desired offset position
relative to the axis 101 of
the housing 136 while rotating the mandrel 102 about the axis 101 of the
housing 136 to orient
the mandrel towards a desired direction, or in other words, to change the tool
face of the mandrel
towards a desired angle. Such a steering assembly provides a better control of
the tool face
orientation and provides borehole doglegs of better quality.
The housing 136 is advantageously configured for not rotating in the wellbore,
for
example by providing on the external surface of the housing a plurality of
stabilizer pads 122
adapted to contact the walls of the wellbore. The pads 122 may have a rugged
contact surface or
can be made of rubber material to provide friction with the wall of the
wellbore and preventing
rotation of the housing. It is preferred that the housing 136 is in a position
independent from the
rotation of the mandrel, the tool face assembly and the deflecting assembly,
such that the housing
136 serves as a reference point for steering. The steering assembly of the
present invention
allows an easier control of the tool face over the whole range of 360 . The
steering assembly of
the present invention also allows the offset of the front extremity of the
mandrel to be varied to
generate a variation of doglegs from small doglegs to high doglegs. The
flexibility of the
steering assembly is due to the pivot stabilizer and that creates a pivot
point for the mandrel
about which the mandrel rotates. This flexibility allows high doglegs.
Despite that the housing is configured for not rotating in the wellbore and is
provided
advantageously with stabilizer pads 122, it can happen that the housing
accidentally rotates in the
wellbore due for example to undesirable friction through the bearings. In
order to prevent
undesirable steering deviations, the housing 136 of the steering assembly is
preferably equipped
by a controller including accelerometers or other measuring means for
measuring the deviation of
the housing 136 relative to its initial tool face and the gravity vector. The
controller is preferably
included in the control electronics assembly 125, and is configured for
measuring deviations of
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the housing angular position, for computing corrections to apply to the
deflecting assembly and
to the tool face assembly in order to steer the bit according to the desired
direction and for
applying these corrections to the deflecting assembly and to the tool face
assembly.
A steering assembly 100 according to a second embodiment of the present
invention
comprises a housing 136 having a longitudinal axis 101 and a mandrel 102
comprising a front
connecting extremity 103 and a rear connecting extremity 104, the mandrel 102
passing through
the said housing 136 and arranged in a first position coaxially to the said
longitudinal axis 101, a
deflector device for giving a side force to the said mandrel 102 in the
housing 136 such as to
bring the said front connecting extremity 103 of the said mandrel 102 offset
from the said
longitudinal axis 101, characterized in that it further comprises a pivot
stabilizer 131 connected
to the rear extremity 104 of the mandrel. The pivot stabilizer sub 131 gives
more flexibility to the
steering assembly. The deflector device can be any deflector device known in
the art such as a set
of pistons or pads pushing the mandrel 102 offset from the longitudinal axis
101 of the housing
136, or the deflector device can be a deflecting assembly as disclosed herein
above. Upon a side
force on the mandrel 102, the mandrel 102 rotates about the pivot point of the
pivot stabilizer and
bending of the mandrel is prevented. Thanks to that feature also, a wellbore
can be drilled with
higher doglegs.
Preferably, the said pivot stabilizer is arranged outside of the housing 136.
The steering
assembly is simpler to build, comprises less parts in the housing, and removal
of the pivot
stabilizer sub is facilitated for maintenance.
In another configuration of the second embodiment of the invention, the front
extremity
103 of the mandrel 102 is connected to a pivot sub 135 which is connected to a
near bit stabilizer
sub 133 which is connected to a drill bit 200.
Preferably, the said housing 136 is configured for not rotating within the
wellbore and serves
as a reference point for steering the bit.
Preferably, the steering assembly comprises:
- a deflecting assembly for giving a side force to the said mandrel
102 into the housing
136 such as to bring the said front connecting extremity 103 of the said
mandrel 102
offset from the said longitudinal axis 101, and
- a tool face assembly for rotating the said front connecting extremity 103 of
the said
mandrel 102 towards a desired direction;
the said mandrel 102 being rotatable relative to the said housing, the said
deflecting assembly and
the said tool face assembly.
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Preferably, the steering assembly comprises a control device configured for
measuring any
undesirable rotation of the housing in the wellbore, calculating the
correction to apply to steer the
bit in the desired direction and to apply these corrections to the said
deflecting assembly and tool
face assembly.
Preferably, the tool face assembly and the deflecting assembly may comprise
any one of
the features listed herein above for the steering assembly according to the
first embodiment of the
present invention.
Preferably, the second embodiment of the steering assembly comprises any one
of the
features of the first embodiment of the present invention.
According to a second aspect, the present invention is related to a method for
drilling
directionally wellbore by providing in a drillstring a steering assembly 100
according to any one
of the aforementioned embodiments, and wherein the direction of drilling is
changed by
operating the said deflecting assembly.
Preferably, the direction of drilling is further changed by operating the said
tool face
assembly.
More preferably, the direction of drilling is changed by operating in the same
time the
deflecting assembly and the tool face assembly.
In an embodiment of the method of the present invention, the steering assembly
100 is used
in a push the bit configuration with the said front extremity 103 of the
mandrel 102 connected to
a drill bit 200.
In an alternative embodiment of the present invention, the steering assembly
100 is used in a
point the bit configuration wherein the said front extremity 103 of the
mandrel 102 is connected
to a pivot sub 135 which is connected to a near bit stabilizer 133 having
blades 134 away from
the pivot point 139 of the pivot sub 135, the near bit stabilizer 133 being
connected to a drill bit
200.
Also, a first section of a wellbore can be drilled by using the steering
assembly in a push the
bit configuration and a second section of a wellbore can be drilled by using
the steering assembly
in a point the bit configuration or inversely.
STEERING ASSEMBLY USING DEFLECTION ASSEMBLY AND TOOL FACE SLEEVE
In another implementation, a steering assembly may be used in a drill string
for steering a
drill bit in a directional wellbore, where the steering assembly may include a
deflection assembly
and a tool face sleeve. Similar to the components of the steering assembly
100, the deflection
assembly may be used to deflect a mandrel at a desired offset position
relative to an axis of the
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steering assembly, and the tool face sleeve may be used to orient the mandrel
towards a desired
direction (i.e., change a tool face angle of the mandrel), as further
described below.
For example, Figure 6 illustrates a cross-sectional view of a portion of a
steering assembly
600 in accordance with implementations of various techniques described herein.
As shown, the
steering assembly 600 may include a housing 605 and a mandrel 610, where the
mandrel 610
may be disposed within and configured to pass through the housing 605. The
mandrel 610 may
also be rotatable relative to the housing 605. Further, the housing 605 may
have a longitudinal
axis (not shown) that is similar to the longitudinal axis 101 described above,
and the mandrel 610
may have a mandrel axis 611 that is similar to the mandrel axis 101' described
above. In one
implementation, the housing 605 may be configured to not rotate within the
wellbore, similar to
the housing 136 described above. In one such implementation, one or more pads
606 (similar to
pads 122) may be used to prevent such rotations and to centralize this housing
605 in the
borehole.
The mandrel 610 may be similar to the mandrel 102, described above, in that it
may have a
front connecting extremity configured to couple to a drill bit (not shown),
and it may have a rear
connecting extremity configured to couple to a drill string (not shown). The
front connecting
extremity may be positioned farther downhole relative to the rear connecting
extremity.
As is also shown, the steering assembly 600 may include a deflection assembly
620 and a
tool face sleeve 650. As mentioned above, the deflection assembly 620 may be
configured to
deflect the mandrel 610 at a desired offset position relative to the
longitudinal axis of the housing
605. In addition, the tool face sleeve 650 may be configured to orient the
mandrel 610 towards a
desired direction (i.e., change a tool face angle of the mandrel 610).
The portion of the steering assembly 600 shown in Figure 6 may be similar to
the second
section of the steering assembly 100 shown in Figure 2b and as described
above. In particular,
though not shown in Figure 6, the rear connecting extremity of the mandrel 610
may be similarly
coupled to a pivot stabilizer sub, and/or the front connecting extremity of
the mandrel 610 may
be similarly coupled to a pivot sub, near bit stabilizer, blades, and/or the
drill bit. Further, though
not shown in Figure 6, the mandrel 610 may be similarly coupled to the housing
605 via a
spherical seat and bearings. Additionally, though not shown in Figure 6, the
steering assembly
600 may similarly include compartments, enclosures, batteries, and control
electronic assemblies
configured to communicate with the surface and to operate one or more motors
described below.
These compartments, enclosures, batteries, and control electronic assemblies
may be disposed
inside the housing 605 at a position uphole relative to the portion of the
steering assembly 600
shown in Figure 6.
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Similar to the steering assembly 100, the steering assembly 600 may include a
controller
and/or computing system configured to measure deviations of the housing
angular position, to
compute corrections to apply to the deflection assembly and to the tool face
sleeve in order to
steer the bit according to the desired direction, and to apply these
corrections to the deflection
assembly and to the tool face sleeve. Any sensors known to those skilled in
the art may be used
to steer the bit and/or measure such deviations.
As shown in Figure 6, the tool face sleeve 650 may be coupled to an inner
surface of the
housing 605 and configured to be arranged around the mandrel 610. In one
implementation, the
tool face sleeve 650 may be positioned proximate to the front connecting
extremity (not shown)
of the mandrel 610. A bore of the tool face sleeve 650 may have an axis 651,
which may
hereinafter be referred to as a deflection axis, that is inclined relative to
the longitudinal axis of
the housing 605. The deflection axis 651 may be similar in functionality and
location to the
second axis 137 described above with respect to Figures 2b-5. As further
described later, an
inner surface of the tool face sleeve 650 may be coupled to an outer surface
of a deflection sleeve
632.
In addition, and as further described later, the tool face sleeve 650 may be
rotated, which may
orient the mandrel 610 towards a desired direction (i.e., change a tool face
angle of the mandrel
610). Other components used to operate the tool face sleeve 650 may not be
shown in Figure 6,
but are discussed later.
As also shown in Figure 6, the deflection assembly 620 may include a
deflection motor 622, a
deflection gear 626, a ring gear 628, a lead screw 630, the deflection sleeve
632, and a bearing
carriage 640. The deflection assembly 620 may include other components, as
further described
later. The deflection sleeve 632 may be configured to be at least partially
disposed within the
housing 605, and may also be configured to be arranged around the mandrel 610.
In particular, a
bore of the deflection sleeve 632 may be coaxial with the longitudinal axis of
the housing 605.
As explained below, components of the deflection assembly 620 may be used to
translate the
deflection sleeve 632 along the longitudinal axis of the housing 605.
As shown, a downhole portion of the deflection sleeve 632 may be coupled to
the bearing
carriage 640. The deflection sleeve 632 may be coupled to the bearing carriage
640 using any
implementation known to those skilled in the art. For example, an outer
surface of the carriage
640 may be coupled to one or more segments of the deflection sleeve 632, where
such segments
have a narrower outer diameter than the remaining portion of the deflection
sleeve 632.
The bearing carriage 640 may be disposed within the inclined bore of the tool
face sleeve
650, and may also be configured to be arranged around the mandrel 610. The
carriage 640 may
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be coaxial with the deflection axis 651, such that the carriage 640 may be
configured to move
within the tool face sleeve 650 along its deflection axis 651.
In some implementations, the bearing carriage 640 may be similar in design and
construction
to the assembly represented by the deflecting sleeve 107, spherical seat 121a,
and the ball bearing
121b discussed above. In particular, a spherical seat 641 and a ball bearing
of the carriage 640
may be configured to allow free rotation of the mandrel 610 within the
carriage 640.
As such, the mandrel 610 may be deflected by the carriage 640 as the bearing
carriage 640
translates along the deflection axis 651 of the tool face sleeve 650. As
further described below,
components of the deflection assembly 620 may be used to translate the
deflection sleeve 632
along the longitudinal axis of the housing 605, which, in turn, may lead to a
translation of the
carriage 640 and a deflection of the mandrel 610.
Deflection Assembly
Implementations regarding deflecting the mandrel 610 at a desired or
predetermined offset
position relative to the longitudinal axis of the housing 605 are further
described below. Figure 7
illustrates a cross-sectional enlarged view of the steering assembly 600 in
accordance with
implementations of various techniques described herein. In particular, Figure
7 illustrates further
components of the deflection assembly 620.
As shown, the deflection motor 622 may be included within the housing 605,
such as in one
or more enclosures or compartments along an inner surface of the housing 605.
In one
implementation, the deflection motor 622 may be positioned proximate to the
control electronics
assemblies of the steering assembly 600 in order to facilitate communication
between the motor
622 and the control electronics assemblies.
A shaft 623 may extend downhole to the deflection gear 626, where the shaft
623 may be
used to operate the deflection gear 626. The deflection gear 626 may be any
gear known in the
art, including a pinion gear. In one implementation, the motor 622 may drive
and/or rotate the
shaft 623 in order to drive and/or rotate the deflection gear 626. In one
implementation, when
the motor 622 is operating, both the shaft 623 and the deflection gear 626 may
rotate about an
axis that is parallel to the longitudinal axis (not pictured) of the housing
605.
An outer surface of the deflection gear 626 may be configured to engage with
an outer
diameter of the ring gear 628. The ring gear 628 may be held in place using
one or more
bearings 627 coupled to the inner surface of the housing 605. In particular,
using the bearings
627, the ring gear 628 may be configured to rotate around the longitudinal
axis (not pictured) of
the housing 605 while avoiding any translational movement along the
longitudinal axis. Further,
the outer diameter of the ring gear 628 may be geared in such a manner that
the ring gear 628 is
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configured to rotate as the deflection gear 626 rotates. In one
implementation, an inner diameter
of the ring gear 628 may be threaded, where any threading known to those
skilled in the art may
be used. In another implementation, the inner diameter of the ring gear 628
may be rotationally
coupled to a sleeve (not shown), where the sleeve may have an inner diameter
that is threaded.
In one implementation, the lead screw 630 may be disposed on the inner
diameter of the ring
gear 628, such that an outer diameter of the lead screw 630 is configured to
threadably engage
with the threaded inner diameter of the ring gear 628. In another
implementation, the lead screw
630 may be disposed on the inner diameter of a sleeve that is rotationally
coupled to the inner
diameter of the ring gear 628, such that an outer diameter of the lead screw
630 is configured to
threadably engage with the threaded inner diameter of the sleeve. Furthermore,
the lead screw
630 may be keyed (not shown) to the outer housing 605 such that rotation is
prevented, but linear
translation is allowed. In one implementation, the outer diameter of the lead
screw 630 may be
threaded in a similar manner as the inner diameter of the ring gear 628.
As such, as the ring gear 628 rotates, the threaded engagement with the lead
screw 630, along
with the rotational constraint imposed from the key between the lead screw 630
and outer
housing 605, cause the lead screw 630 to translate along the longitudinal axis
of the housing 605.
Moreover, the lead screw 630 may translate in a particular direction within
the housing 605 based
on a particular direction of the rotation of the ring gear 628.
Additionally, as shown in Figure 7, the lead screw 630 may be configured to be
arranged
around the deflection sleeve 632 and the mandrel 610. In one implementation,
as the lead screw
630 translates along the longitudinal axis, the deflection sleeve 632 may be
configured to
translate in a same direction. As shown, the lead screw 630 may be disposed
around the
deflection sleeve 632 between a pair of abutments 631 protruding from an outer
surface of the
deflection sleeve 632. In addition, a pair of bearings 633 may be positioned
between the
abutments 631 and each end of lead screw 630. An abutment 631 may represent a
shoulder
extending from the outer surface of the deflection sleeve 632, a snap ring, or
any other
implementation known to those skilled in the art. The bearings 633 may be any
bearings know to
those skilled in the art.
As such, as the lead screw 630 translates along the longitudinal axis due to a
rotation of the
ring gear 628, an end of the lead screw 630 may come into contact with an
abutment and/or
bearing 633 of the deflection sleeve 632. Accordingly, the translation of the
lead screw 630 may
cause the deflection sleeve 632 to move in conjunction with the lead screw
630. In one
implementation, the translation of the deflection sleeve 632 may be limited to
a travel distance
between a downhole end of a ring gear634 and an uphole end of the tool face
sleeve 650 within
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the housing 605, where the abutments 631 of the sleeve 632 may contact the
ring gear 634 or the
uphole end of the tool face sleeve 650. The ring gear 634 may be positioned
farther uphole than
the tool face sleeve 650. The ring gear 634 is described in further detail in
a later section.
In a further implementation, the lead screw 630 and the deflection sleeve 632
may rotate
independently of each other. In particular, due to a clearance between an
inner diameter of the
lead screw 630 and an outer diameter of the deflection sleeve 632, along with
the presence of the
bearings 633, the lead screw 630 may rotate freely around the deflection
sleeve 632, and the
deflection sleeve 632 may similarly rotate freely within the lead screw 630.
As such, it may be
said that the lead screw 630 and the deflection sleeve 632 may be axially
coupled to one another,
but not rotationally coupled.
In addition, as noted above, a portion of the deflection sleeve 632 may be
coupled to the
bearing carriage 640. As such, a translational movement of the lead screw 630
may lead to the
deflection sleeve 632 pushing the bearing carriage 640 in the same direction.
However, due to
the inclined nature of the bore of the tool face sleeve 650, the bearing
carriage 640 may move
along the deflection axis 651 of the sleeve 650. In one implementation, as the
bearing carriage
640 moves along the deflection axis 651 in a downhole direction, the bearing
carriage 640 may
apply a side force to the mandrel 610, thereby deflecting the axis 611 of
mandrel 610 relative to
the longitudinal axis of the housing 605. Accordingly, the deflection assembly
620 and its
components (e.g., the ring gear 628, the lead screw 630, and the deflection
sleeve 632) can be
used to deflect the mandrel 610 at a desired offset position relative to the
longitudinal axis of the
housing 605.
In one example operation, the components of the steering assembly 600 may
initially be
positioned as shown in Figures 6-7. In particular, the lead screw 630 may be
at a first position,
such that the most uphole abutment 631 of the deflection sleeve 632 may be
positioned
proximate to the ring gear 634. Accordingly, deflection sleeve 632 may not
have pushed the
bearing carriage 640 far into the inclined bore of the tool face sleeve 650.
In such instances, the
bearing carriage 640 may have applied little to no side force to the mandrel
610, leading to little
to no deflection of axis 611 of the mandrel 610 relative to the longitudinal
axis of the housing
605. For such instances, the mandrel 610 may be at a zero offset position
relative to the
longitudinal axis.
However, the motor 622 may subsequently drive the shaft 623 to rotate the
deflection gear
626, thereby causing a rotation of the ring gear 628. As the ring gear 628
rotates, the threaded
engagement with the lead screw 630 may lead to a rotation of the lead screw
630 about the
longitudinal axis (not pictured) of the housing 605. The lead screw 630 may
rotate until it
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reaches a position as shown in Figures 8 and 9. Figure 8 illustrates a cross-
sectional enlarged
view of the steering assembly 600 in accordance with implementations of
various techniques
described herein, and Figure 9 illustrates a cross-sectional view of a portion
of a steering
assembly 600 in accordance with implementations of various techniques
described herein.
As shown, the lead screw 630 may have translated in a direction farther
downhole than its
initial position. Accordingly, the deflection sleeve 632 may also have
similarly translated farther
downhole to a new position in conjunction with the lead screw 630. Moreover,
the deflection
sleeve 632 may have pushed the bearing carriage 640 as the sleeve 632 moved to
this new
position. As shown, the bearing carriage 640 may have moved farther downhole
along the
deflection axis 651 of the sleeve 650, such that the bearing carriage 640 may
have applied a side
force to the mandrel 610. As a result of the applied side force, the axis 611
of the mandrel 610
has been deflected to an offset position relative to the longitudinal axis of
the housing 605, as
shown in Figure 9. By using the deflection assembly 620 to deflect the mandrel
610, the steering
assembly 600 may be used to achieve higher doglegs during drilling of the
wellbore. In some
implementations, a controller or computing system may be used to operate the
deflection motor
622 in a particular manner such that the mandrel 610 is deflected to a
specified or predetermined
offset position relative to the longitudinal axis of the housing 605.
In one implementation, the steering assembly 600 may be sealed along the tool
from a
position uphole from reference point 690. Such a seal may allow for a portion
of the deflection
assembly 620, including the deflection motor 622, the deflection gear 626, the
ring gear 628, the
lead screw 630, at least part of the deflection sleeve 632, and their
associated components to
operate in a sealed, hydraulic oil-filled volume.
Toolface Sleeve
Implementations regarding orienting the mandrel 610 towards a desired
direction (i.e., change
a tool face angle of the mandrel 610) using the tool face sleeve 650 are
further described below.
For example, Figure 10 illustrates a cross-sectional view of the steering
assembly 600 in
accordance with implementations of various techniques described herein. In
particular, Figure 10
illustrates the tool face sleeve 650 and further associated components.
Further, Figure 10 shows
a tool face motor 682, a shaft 683, a tool face gear 686, a ring gear 634, the
lead screw 630, the
deflection sleeve 632, the bearing carriage 640, the tool face sleeve 650, and
bearings 691.
It should be noted that Figure 10 illustrates a different cross-section of the
tool than that
illustrated in Figures 6-9. In particular, as shown in Figure 11, a line 1101
may bisect the
assembly 600 such that a cross-section of the assembly 600 through the motor
622 is shown.
This is represented in Figures 6-9. Further, a line 1102 may bisect the
assembly 600 such that a
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cross-section of the assembly 600 through the motor 682 is shown. This is
represented in Figures
and 12. Figure 11 illustrates a front cross-sectional view of the steering
assembly 600 in
accordance with implementations of various techniques described herein.
As shown in Figure 10, a tool face motor 682 may be included within the
housing 605, such
5
as in one or more enclosure or compartments along an inner surface of the
housing 605. In one
implementation, the tool face motor 682 may be positioned proximate to the
control electronics
assemblies of the steering assembly 600 in order to facilitate communication
between the motor
682 and the control electronics assemblies.
A shaft 683 may extend downhole to the tool face gear 686, where the shaft 683
may be used
10
to operate the tool face gear 686. The tool face gear 686 may be any gear
known in the art,
including a pinion gear. In one implementation, the motor 682 may drive and/or
rotate the shaft
683 in order to drive and/or rotate the tool face gear 686. In one
implementation, when the motor
682 is operating, both the shaft 683 and the tool face gear 686 may rotate
about an axis that is
parallel to the longitudinal axis (not pictured) of the housing 605.
An outer surface of the tool face gear 686 may be configured to engage with an
outer
diameter of the ring gear 634. The ring gear 634 may be held in place using
one or more
bearings. In particular, using the bearings, the ring gear 634 may be
configured to rotate around
the longitudinal axis (not pictured) of the housing 605 while avoiding any
translational
movement along the longitudinal axis. Further, the outer diameter of the ring
gear 634 may be
geared in such a manner that the outer diameter is configured to rotate as the
tool face gear 686
rotates. In addition, an inner diameter of the ring gear 634 may be keyed (not
shown) to the
deflection sleeve 632. As such, as the ring gear 634 rotates, the deflection
sleeve 632 may be
configured to rotate as well, while avoiding any translational movement along
the longitudinal
axis.
In addition, the deflection sleeve 632 may configured to be rotationally
coupled to the tool
face sleeve 650 using any implementation known to those skilled in the art. As
such, when the
deflection sleeve 632 rotates in a particular direction about the longitudinal
axis, then the tool
face sleeve 650 may be configured to rotate in the same direction. As shown in
Figure 10, an
inner surface of the tool face sleeve 650 may be rotationally coupled to an
outer surface of the
deflection sleeve 632 within the housing 605. In one implementation, the inner
surface of the
tool face sleeve 650 may be keyed to the outer surface of the deflection
sleeve 632, such that the
tool face sleeve 650 rotates together with the deflection sleeve 632. In
addition, one or more
bearings 691 known to those skilled in the art, such as a thrust bearing, may
be arranged between
the inner surface of the housing 605 and the tool face sleeve 650.
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In one implementation, the tool face sleeve 650 may be similar to the second
sleeve section
106b of the orienting sleeve 106, as described above with respect to Figures
2a-4. In particular,
an outer surface of the tool face sleeve 650 may be cylindrically coaxial to
the longitudinal axis
of the housing 605. The tool face sleeve 650 may also have an outer diameter
that is configured
to prevent debris of the wellbore to penetrate within the housing 605. For
example, the outer
diameter of the tool face sleeve 650 may be superior or equal to the outer
diameter of the end of
the housing 605. In another example, the outer diameter of the tool face
sleeve 650 may be
substantially equal or superior to the inner diameter of the end of the
housing 605. Further,
because of the inclination of the bore of the tool face sleeve 650, the outer
diameter of the tool
face sleeve 650 may be superior to the outer diameter of the deflection sleeve
632.
In another implementation, the tool face sleeve 650 may be partially included
in the housing
605, with the deflection sleeve 632 arranged inside of the housing 605 and the
tool face sleeve
650 arranged outside of the housing 605. In a further implementation, the tool
face sleeve 650
may be rotatable relative to the housing 605.
To change a desired direction of the mandrel 610 (i.e., change a tool face
angle of the
mandrel 610), the tool face motor 682, the shaft 683, the tool face gear 686,
the ring gear 634, the
deflection sleeve 632, the bearing carriage 640, and the tool face sleeve 650
may be used. In
particular, the tool face motor 682 may be used to rotate the deflection
sleeve 632, as mentioned
above. In addition, when the deflection sleeve 632 rotates in a particular
direction about the
longitudinal axis, then the tool face sleeve 650 may be configured to rotate
in the same direction.
As the tool face sleeve 650 rotates, the deflection axis 651 of the tool face
sleeve 650 may rotate
relative to the longitudinal axis of the housing 650. The bearing carriage
640, which may be
coaxial with the deflection axis 651, may also rotate with the rotation of the
tool face sleeve 650.
Accordingly, the angle of the bearing carriage 640 and the deflection axis 651
relative to the
longitudinal axis may also change, which may alter the direction at which the
mandrel 610 may
be deflected relative to the longitudinal axis.
As such, the direction of the mandrel 610 may change as the tool face sleeve
650 rotates.
Accordingly, the tool face motor 682, the deflection sleeve 632, the tool face
sleeve 650, and
their associated components may be used to change the direction of the mandrel
610 (i.e., change
a tool face angle of the mandrel 610). In one implementation, the deflection
sleeve 632 may bear
most of the torsional load relative to the other components of the steering
assembly 600 when
changing a tool face angle of the mandrel 610.
In one example operation, the components of the steering assembly 600 may
initially be
positioned as shown in Figure 10. The motor 682 may drive the shaft 683 to
rotate the tool face
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gear 686, thereby causing a rotation of the ring gear 634. As the ring gear
634 rotates, the
deflection sleeve 632 may rotate in a similar fashion. Likewise, a rotation of
the deflection
sleeve 632 may lead to a rotation of the coupled tool face sleeve 650, thereby
rotating the
deflection axis 651 of sleeve 650 relative to the longitudinal axis. For
example, the tool face
sleeve 650 and its deflection axis 651 may have rotated 180 degrees, as shown
in Figure 12.
Figure 12 illustrates a cross-sectional view of the steering assembly 600 in
accordance with
implementations of various techniques described herein. In such an example,
where a deflected
mandrel 610 has rotated 180 degrees, the tool face angle of the mandrel may
have also changed
180 degrees.
As mentioned above, the lead screw 630 and the deflection sleeve 632 may
rotate
independently of each other. In particular, due to a clearance between an
inner diameter of the
lead screw 630 and an outer diameter of the deflection sleeve 632, along with
the bearings 633,
the lead screw 630 may rotate freely around the deflection sleeve 632, and the
deflection sleeve
632 may similarly rotate freely within the lead screw 630. Accordingly,
rotating the tool face
.. sleeve 650 and the deflection sleeve 632 for purposes of changing a tool
face angle of the
mandrel 610 may have no effect on the rotation of the lead screw 630, as the
lead screw 630 may
rotate independently of the tool face sleeve 650 and the deflection sleeve
632. As such, changing
the tool face angle of the mandrel 610 may have no effect on the translation
of the lead screw
630, deflection sleeve 632, or bearing carriage 640, which means the
deflection of the mandrel
610 is unaffected.
In some implementations, a controller or computing system may be used to
operate the tool
face sleeve 650 and associated components (e.g., motor 682, deflection sleeve
632, etc.) in a
particular manner such that the mandrel 610 is oriented to a specified or
predetermined direction
(i.e., a specified or predetermined tool face angle). Further, as mentioned
above, the steering
.. assembly 600 may be sealed from a position uphole from reference point 690.
Such a seal may
allow for the coupling of the deflection sleeve 632 and the tool face sleeve
650 to be positioned
within a sealed, hydraulic oil-filled volume.
Implementations relating to a steering assembly used in a drill string for
steering a drill bit in
a directional wellbore are disclosed herein. In particular, the steering
assembly may include a
deflection assembly used to deflect a mandrel at a desired offset position
relative to an axis of the
steering assembly, and may include a tool face sleeve used to orient the
mandrel towards a
desired direction (i.e., change a tool face angle of the mandrel).
In one implementation, a lead screw and a deflection sleeve may rotate
independently of each
other. In particular, the lead screw may rotate freely around the deflection
sleeve, and the
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deflection sleeve may similarly rotate freely within the lead screw. As such,
it may be said that
the lead screw and the deflection sleeve may be axially coupled to one
another, but not
rotationally coupled.
Accordingly, rotating the tool face sleeve and the deflection sleeve for
purposes of changing
a tool face angle of the mandrel may have no effect on the rotation of the
lead screw, as the lead
screw may rotate independently of the tool face sleeve and the deflection
sleeve. As such,
changing the tool face angle of the mandrel may have no effect on the
translation of the lead
screw, deflection sleeve, or bearing carriage, which means the deflection of
the mandrel is
unaffected. It follows that implementations for the steering assembly
described herein may
consume less power than other assemblies in which changing a tool face angle
may affect a
deflection of the mandrel. For those other assemblies, both the tool face and
deflection
mechanisms would need to be operated to avoid a change in deflection of the
mandrel. This may
particularly be an issue for those other assemblies in which tool face angle
is changed often,
while deflection may be held for longer periods.
Furthermore, as described above, many components of the steering assembly
described
herein may be disposed within a sealed, hydraulic oil-filled volume. Other
assemblies may
position such components in mud, which may be less clean than hydraulic oil.
By using
hydraulic oil rather than mud, the implementations described herein may allow
for improved
reliability, improved service life, finer pitch lead screws, finer positioning
of deflection of the
mandrel, less stress on the electric motor, and better resistance to back
driving the motor and gear
device.
COMPUTING SYSTEM
Figure 13 illustrates a block diagram of a hardware configuration 1300 in
which one or more
various technologies described herein may be incorporated and practiced. The
hardware
configuration 1300 can be used to implement the computing system and/or
controller discussed
above. The hardware configuration 1300 can include a processor 1310, a memory
1320, a
storage device 1330, and an input/output device 1340. Each of the components
1310, 1320,
1330, and 1340 can, for example, be interconnected using a system bus 1350.
The processor
1310 can be capable of processing instructions for execution within the
hardware configuration
1300. In one implementation, the processor 1310 can be a single-threaded
processor. In another
implementation, the processor 1310 can be a multi-threaded processor. The
processor 1310 can
be capable of processing instructions stored in the memory 1320 or on the
storage device 1330.
The memory 1320 can store information within the hardware configuration 1300.
In one
implementation, the memory 1320 can be a computer-readable medium. In one
implementation,
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the memory 1320 can be a volatile memory unit. In another implementation, the
memory 1320
can be a non-volatile memory unit.
In some implementations, the storage device 1330 can be capable of providing
mass storage
for the hardware configuration 1300. In one implementation, the storage device
1330 can be a
computer-readable medium. In various different implementations, the storage
device 1330 can,
for example, include a hard disk device/drive, an optical disk device, flash
memory or some other
large capacity storage device. In other implementations, the storage device
1330 can be a device
external to the hardware configuration 1300. Various implementations for the
memory 1320
and/or the storage device 1330 are further discussed below.
The input/output device 1340 can provide input/output operations for the
hardware
configuration 1300. In one implementation, the input/output device 1340 can
include one or
more display system interfaces, sensors and/or data transfer ports.
The subject matter of this disclosure, and/or components thereof, can be
realized by
instructions that upon execution cause one or more processing devices to carry
out the processes
and functions described above. Such instructions can, for example, comprise
interpreted
instructions, such as script instructions, e.g., JavaScript or ECMAScript
instructions, or
executable code, or other instructions stored in a computer readable medium.
Implementations of the subject matter and the functional operations described
in this
specification can be provided in digital electronic circuitry, or in computer
software, firmware, or
hardware, including the structures disclosed in this specification and their
structural equivalents,
or in combinations of one or more of them. Embodiments of the subject matter
described in this
specification can be implemented as one or more computer program products,
i.e., one or more
modules of computer program instructions encoded on a tangible program carrier
for execution
by, or to control the operation of, data processing apparatus.
A computer program (also known as a program, software, software application,
script, or
code) can be written in any form of programming language, including compiled
or interpreted
languages, or declarative or procedural languages, and it can be deployed in
any form, including
as a stand-alone program or as a module, component, subroutine, or other unit
suitable for use in
a computing environment. A computer program does not necessarily correspond to
a file in a file
system. A program can be stored in a portion of a file that holds other
programs or data (e.g., one
or more scripts stored in a markup language document), in a single file
dedicated to the program
in question, or in multiple coordinated files (e.g., files that store one or
more modules, sub
programs, or portions of code). A computer program can be deployed to be
executed on one
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computer or on multiple computers that are located at one site or distributed
across multiple sites
and interconnected by a communication network.
The processes and logic flows described in this specification can be performed
by one or
more programmable processors executing one or more computer programs to
perform functions
by operating on input data and generating output thereby tying the process to
a particular
machine, e.g., a machine programmed to perform the processes described herein.
The processes
and logic flows can also be performed by, and apparatus can also be
implemented as, special
purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an
ASIC (application
specific integrated circuit).
Computer readable media (e.g., memory 1320 and/or the storage device 1330)
suitable for
storing computer program instructions and data may include all forms of non-
volatile memory,
media, and memory devices, including, by way of example, any semiconductor
memory devices
(e.g., EPROM, EEPROM, solid state memory devices, and flash memory devices);
any magnetic
disks (e.g., internal hard disks or removable disks); any magneto optical
disks; and any CD-ROM
and DVD-ROM disks. The processor and the memory can be supplemented by, or
incorporated
in, special purpose logic circuitry.
The discussion above is directed to certain specific implementations. It is to
be understood
that the discussion above is only for the purpose of enabling a person with
ordinary skill in the art
to make and use any subject matter defined now or later by the patent "claims"
found in any
issued patent herein.
It is specifically intended that the claimed invention not be limited to the
implementations
and illustrations contained herein, but include modified forms of those
implementations including
portions of the implementations and combinations of elements of different
implementations as
come within the scope of the following claims. It should be appreciated that
in the development
of any such actual implementation, as in any engineering or design project,
numerous
implementation-specific decisions may be made to achieve the developers'
specific goals, such as
compliance with system-related and business related constraints, which may
vary from one
implementation to another. Moreover, it should be appreciated that such a
development effort
might be complex and time consuming, but would nevertheless be a routine
undertaking of
design, fabrication, and manufacture for those of ordinary skill having the
benefit of this
disclosure. Nothing in this application is considered critical or essential to
the claimed invention
unless explicitly indicated as being "critical" or "essential."
In the above detailed description, numerous specific details were set forth in
order to provide
a thorough understanding of the present disclosure. However, it will be
apparent to one of
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ordinary skill in the art that the present disclosure may be practiced without
these specific details.
In other instances, well-known methods, procedures, components, circuits and
networks have not
been described in detail so as not to unnecessarily obscure aspects of the
embodiments.
It will also be understood that, although the terms first, second, etc. may be
used herein to
describe various elements, these elements should not be limited by these
terms. These terms are
only used to distinguish one element from another. For example, a first object
or step could be
termed a second object or step, and, similarly, a second object or step could
be termed a first
object or step, without departing from the scope of the invention. The first
object or step, and the
second object or step, are both objects or steps, respectively, but they are
not to be considered the
same object or step.
The terminology used in the description of the present disclosure herein is
for the purpose of
describing particular implementations only and is not intended to be limiting
of the present
disclosure. As used in the description of the present disclosure and the
appended claims, the
singular forms "a," "an" and "the" are intended to include the plural forms as
well, unless the
context clearly indicates otherwise. It will also be understood that the term
"and/or" as used
herein refers to and encompasses any and all possible combinations of one or
more of the
associated listed items. It will be further understood that the terms
"includes," "including,"
"comprises" and/or "comprising," when used in this specification, specify the
presence of stated
features, integers, steps, operations, elements, and/or components, but do not
preclude the
presence or addition of one or more other features, integers, steps,
operations, elements,
components and/or groups thereof.
As used herein, the term "if' may be construed to mean "when" or "upon" or "in
response to
determining" or "in response to detecting," depending on the context.
Similarly, the phrase "if it
is determined" or "if [a stated condition or event] is detected" may be
construed to mean "upon
determining" or "in response to determining" or "upon detecting [the stated
condition or event]"
or "in response to detecting [the stated condition or event]," depending on
the context. As used
herein, the terms "up" and "down"; "upper" and "lower"; "upwardly" and
downwardly"; "below"
and "above"; and other similar terms indicating relative positions above or
below a given point or
element may be used in connection with some implementations of various
technologies described
herein.
While the foregoing is directed to implementations of various technologies
described herein,
other and further implementations may be devised without departing from the
basic scope
thereof. Although the subject matter has been described in language specific
to structural features
and/or methodological acts, it is to be understood that the subject matter
defined in the appended
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claims is not limited to the specific features or acts described above.
Rather, the specific features
and acts described above are disclosed as example forms of implementing the
claims.
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